Integrated circuits are being developed which have large numbers of discrete components in very small areas and which operate at faster and faster speeds. As the number of components and the speed of those components have increased, the power at which the integrated circuit chips have operated has also increased. High power operation generates heat which must be dissipated into the atmosphere to prevent overheating of the integrated circuit.
As an integrated circuit heats up, the operating characteristics of the circuit changes. Thus it is important in the large scale integration industry to provide a heat exchanger which will maintain the temperature of the integrated circuit within an acceptable range.
Prior art heat exchangers can be loosely divided into two broad categories. The first category is for liquid-cooled systems which flow a liquid coolant across heat sinks mounted with the integrated circuits. The second category includes air or gas cooling mediums which are blown across the heat sinks of the integrated circuits.
The prior art liquid-cooled systems while providing good heat transfer capability are very bulky, heavy and messy when used in connection with integrated circuits. Furthermore the liquid-cooled systems require that the heat be first transferred from a heat sink connected to the integrated circuit to the liquid cooling medium and then from the liquid cooling medium into the atmosphere. Thus there is required additional equipment for radiating heat from the cooling medium to the atmosphere.
On the other hand, air-cooled systems in the prior art while relatively lightweight and simple compared to liquid-cooled systems, are limited by the amount of heat which can effectively be dissipated directly into the atmosphere. The prior art air-cooled system is exemplified by U.S. Pat. No. 4,115,837 ('837 patent) owned by Amdahl Corporation which is also the assignee of the present invention. In the '837 patent, the heat exchanger comprises a cooling stud made of a solid material that conducts heat readily which is attached to a substrate supporting an integrated circuit chip. The heat is conducted into the cooling stud and air is forced across the cooling stud to remove heat to the atmosphere. Cooling fins can be attached to the cooling stud to increase the surface area for dissipation of heat by the heat exchanger in that air-cooled system. The arrangement of the '837 patent has proved satisfactory for integrated circuits which generate smaller amounts of heat. However as the amount of heat generated by integrated circuits increases, the prior art air-cooled system becomes less useful.
Accordingly, there is a need for a heat exchanger system for integrated circuits which will dissipate large amounts of heat using an air or gas cooling medium, or on the other hand, which will require small amounts of liquid cooling medium in order to dissipate large amounts of heat.